1. Field of the Invention
The present invention relates generally relates to the technical field of energy generation and particularly to the field of energy generating devices for converting ocean wave energy to electrical energy.
2. Description of the Prior Art
Ocean waves are an attractive source of renewable energy. Ocean wave energy is abundant, more constant than wind and solar energy, well distributed around the globe and near much of the world""s population. Nonetheless, little use has been made of ocean wave energy due to the difficulties in converting that energy into a useful form such as electricity.
Most conventional technologies relating to generating electricity from ocean waves focus on extracting ocean wave energy from the motion of the ocean waves as the ocean waves migrate through the energy generating device, either using moving flows or using wind turbines driven by air trapped in enclosures above the waves.
The following nine (9) references are believed to be pertinent to this field of art:
1. U.S. Pat. No. 2,501,696 issued to E. Souczek on Mar. 28, 1950 for xe2x80x9cStream Turbingxe2x80x9d (hereafter the xe2x80x9cSouczek patentxe2x80x9d);
2. U.S. Pat. No. 3,209,156 issued to A. D. Struble, Jr. on Sep. 28, 1965 for xe2x80x9cUnderwater Generatorxe2x80x9d (hereafter the xe2x80x9cStruble patentxe2x80x9d);
3. U.S. Pat. No. 3,965,364 issued to Gustafson et al. on Jun. 22, 1976 for xe2x80x9cWave Generatorxe2x80x9d (hereafter the xe2x80x9cGustafson patentxe2x80x9d);
4. U.S. Pat. No. 4,045,148 issued to Morin on Aug. 30, 1977 for xe2x80x9cTurbingxe2x80x9d (hereafter the xe2x80x9cMorin patentxe2x80x9d);
5. U.S. Pat. No. 4,383,182 issued to Bowley on May 10, 1983 for xe2x80x9cUnderwater Power Generatorxe2x80x9d (hereafter the xe2x80x9cBowley patentxe2x80x9d);
6. U.S. Pat. No. 4,748,808 issued to Hill on Jun. 7, 1988 for xe2x80x9cFluid Powered Motor-Generator Apparatusxe2x80x9d (hereafter the xe2x80x9cHill patentxe2x80x9d);
7. U.S. Pat. No. 4,850,190 issued to Pitts on Jul. 25, 1989 for xe2x80x9cSubmerged Ocean Current Electrical Generator And Method For Hydrogen Productionxe2x80x9d (hereafter the xe2x80x9cPitts patentxe2x80x9d);
8. U.S. Design Pat. No. Des.261,639 issued to Robinson on Nov. 3, 1981 for xe2x80x9cWater-Driven Electricity Generatorxe2x80x9d (hereafter the xe2x80x9cRobinson Design Patentxe2x80x9d); and
9. PCT Patent Publication No. WO 99/20896 published on Apr. 29, 1999 for xe2x80x9cMethod and Arrangement for Converting Kinetic Energy of Ocean Currents into Rotary Energyxe2x80x9d (hereafter the xe2x80x9cPCT Publicationxe2x80x9d).
The Souczek patent disclosed a stream turbine device. The device includes a an underwater carrier wing structure connected to the stream turbine and adapted to create dynamic buoyancy. The underwater carrier wing structure is connected to one and of an elongated holding device. The other end of the holding device is anchored at the bottom of the water course.
The Struble patent disclosed an underwater generator unit. The unit includes a body portion having waterproofed stator elements mounted in the exterior surface of the body portion. The unit also includes a shaft for rotatively securing an impeller assembly.
The Gustafson patent disclosed a device for utilizing energy stored in wave motion. The device includes a buoyant body on the water surface is anchored so as to permit free, unrestricted vertical movement when acted upon by a heaving wave. An energy collecting device is connected to the buoyant body and located at a depth where the water is not subjected to the vertical wave motion.
The Morin patent disclosed a turbine with a water-driven motive element adapted for being immersed in a body of water. The motive element includes a disc having a density close to that of the water in which it is immersed. The disc is horizontally disposed and has a plurality of cells containing a mixture of liquid and gas and the disc carries on the upper and lower surfaces thereof a plurality of blades which are pivotably movable about a horizontal axis. Each blade has one or more pocket containing a mixture of gas and a liquid such that the density of the blades connected to the upper surface of the disc is less than that of water and the density of the blades connected to the lower surface of the disc is greater than that of water. The disc carries a structure which holds the blades in one direction of pivotal movement when the blades reach a vertical position. Under the action of water current, the blades are driven to their vertical position and effect rotation of the disc, which serves to drive an electrical generator system.
The Bowley patent disclosed an apparatus and method for generating electrical power. The apparatus includes a plurality of power producing modules disposed in a substantially constant velocity ocean current. The method includes the steps of mechanically coupling the output of the modules to drive a single electrical generator.
The Hill patent disclosed a fluid powered motor-generator apparatus. The apparatus includes a generator having a power output and a mechanically driven input. The generator has a generally streamlined motor body rotatably mounted to drive the generator input. The motor has a plurality of radially extending generally V-shaped fins mounted on an outside surface thereof. The fins are mounted on brackets above an outer surface of the motor body and have a convex pointed side facing in the direction of rotation and a concave open side facing in a direction opposite to the direction of rotation. As a result, the action of a stream of fluid on the fins tends to rotate the motor the motor body and drive the generator. If the motor-generator apparatus is mounted in water, the generator can be enclosed in another streamlined body which is anchored tot he bed of the body of water. A third streamlined motor body can be attached to the bottom of the generator body with a plurality of radially extending fins oriented to cause it to rotate opposite to the direction of rotation of the first streamlined motor body.
The Pitts patent disclosed a system and method for generating chemical energy from ocean current energy. The system includes a unique suspension system having a support cable submerged below the ocean surface in an isolation zone remote from the adverse influences of storms and hurricanes. The support cable is submerged by a first anchor which includes guys, buoyancy chambers and guy anchors. A second anchor is provided by generator cable assemblies which suspend a plurality of electric energy generating units and are anchored by means of suspension anchors. Buoyancy provided by modules exert a buoyancy on the suspension system and provides that the basic components of the suspension system essentially support their own weight. In this manner, little or no weight is exerted on support cable by the anchors and generating units suspended. In a preferred embodiment, the generating units are arranged in a matrix of vertical and horizontal rows across the width and along the depth of the ocean current.
The Robinson Design patent disclosed a water-driven electricity generator.
The PCT Publication disclosed a method and arrangement for converting kinetic energy of ocean currents into rotatory energy. The arrangement includes one or more turbines which is arranged to extend substantially vertically form a buoy anchored in such a way in an ocean current that it cannot rotate with the turbine and driving an electric generator or another rotary machine. At the bottom of the turbine, a counterweight is provided to retain the turbine substantially vertically at normal speed of the ocean current but to permit it to assume an inclined position when subjected to temporarily increased current speeds, thereby protecting the turbine form harmful flexural stresses and protecting the rotary machine from being overloaded.
While many of the above cited references have described systems and/or method for generating electric energy from ocean current, these conventional devices are mostly relying on generating electricity from the migration of the ocean waves and focusing on extracting ocean wave energy from the motion of the ocean waves as the ocean waves migrate through the energy generating device, by using either moving flows or using wind turbines driven by air trapped in enclosures above the waves.
In addition, the conventional energy generating devices are also limited in their efficiency by the difficulty in transforming high forces at low speeds into lower forces at higher speeds needed for electricity generation. Most of these conventional devices are further compromised by the necessity of operating at the ocean surface where they are exposed to storms and effected by tides. The installations of such conventional devices tend to be extremely large in comparison with the useful energy produced.
Therefore, it is desirable to provide a novel and unique device for generating electrical energy from ocean waves by utilizing migrating pressure fluctuations in ocean waves by utilizing an excessively buoyant float held beneath the water surface which is free to move horizontally within a limited range.
The present invention is directed to a method of and apparatus for generating electricity from ocean waves by utilizing a float with excessive buoyancy.
Most existing technology aims to extract wave energy from the motion of the liquid as waves migrate through it, either using moving floats or using wind turbines driven by air trapped in enclosures above the waves. Such devices are limited in their efficiency by the difficulty in transforming high forces at low speeds into the lower forces and higher speeds needed for electricity generation. Most of these devices are also compromised by the necessity of operating at the ocean surface where they are exposed to storms and effected by tides. As a general rule, the installations are extremely large in comparison with the useful energy produced.
The present invention is able to overcome many difficulties with existing concepts because it operates on a fundamentally different principle. Rather than being driven by the motion of the water in the waves, it is driven by the pressure fluctuations that travel waves.
In summary, the present invention is directed to a methodology of and an installation for extracting energy from a liquid in which pressure variations are present in the form of migrating surface waves and where it is possible to affix a device to a solid bottom or other structure that does not move vertically with the surface swell. Such an installation is particularly suitable for use in extracting energy from water at sea.
The basic embodiment of the present invention includes a float with excessive buoyancy tethered to the ocean floor. The tether keeps the float beneath the ocean surface in spite of the excessive buoyancy. It also allows the float to move horizontally in response to fluctuations in pressure in the region of the float. The pressure in the water is directly dependent on the depth beneath the surface. The buoyancy of the float creates a force perpendicular to the isobaric surfaces of the ocean wave. The float moves back and forth as the slope of the isobaric surfaces change which occurs as the ocean waves pass over the region where the float is moored. A turbine is held by and moves with the float for generating electricity.
In the present invention, the float with excessive buoyancy goes through the following phases or stages in a typical operation:
At the first stage, the float is directly above the mooring and the isobaric surface is sloping to the right. The float is forced to the right towards the wave trough because of the slope of the isobaric surfaces that mimic the wave shape.
In a second stage, the float is forced back to the left as the wave crest approaches because now the isobaric surfaces are sub-horizontal while the tether is pulling at an angle.
In the next stage, the float is once again directed above the mooring so the tether is not pulling horizontally but the wave crest has passed to the right so that the isobaric surface now slopes to the left. The resultant force vector is still directed to the left and the float continues to move in that direction.
At the last stage as the next trough passes over the float, the buoyancy vector again points vertically and the angle on the tether pulls the float to the right. The float now cycles back to the geometry of the initial stage.
The present invention has many important advantages, including its efficiency in energy conversion, its unobtrusiveness, its unaffectedness by ocean tides, its protection against storms, its omni-directionality, its ability to convert energy from both waves and currents, its scalability, and its simplicity.
Further novel features and other objects of the present invention will become apparent from the following detailed description, discussion and the appended claims, taken in conjunction with the drawings.